I think mine’s Z for Zachariah. The book is insane. A psychological survivalist thriller between a 14 year old girl and a strange man with unknown intent. The movie is… not this. They changed everything meaningful about the characters and lost all the tension. Hope someone does it properly one day. What’s your adaptation peeve?
Watership Down - the Netflix/BBC adaptation. Significant changes to plot that invalidate half the story, and animation from 90s PlayStation games.
As someone who’s read the book several times I turned off the show halfway through the 1st episode and never returned. One of the big problems in the show was making Hazel the leader from the beginning. The point of the book was Hazel never thought of himself as the leader; he always deferred to smarter (Blackberry), stronger (Bigwig) and more insightful (Fiver) rabbits, to make decisions. The big payoff is when Bigwig stands up to General Woundwart [“My Chief rabbit told me to guard this run”] and you realize they all would risk their lives for Hazel.